Network redundancy on Windows 2003 server with two network cards and two gateways.

We have a Windows 2003 server with two network cards and two different gateways.  One gateway is set to a T1 line (192.168.10.252) and the second is set to a Comcast line (192.168.1.254).  When we enter in both gateways, sometimes people get disconnected randomly while connected through either the T1 or the Comcast line.  The server seems to shift randomly between using the T1 gateway for a while, and then switching to the Comcast gateway.  If it is using the Comcast gateway, connections to the T1 IP address aren't accepted.  Then when the server switches back to using the T1 gateway, no one can connect through the Comcast line.

We need to be able to have this server use the T1 connection when the Comcast line is down.  How do we do this using the two network cards present in the system?

Secondly, how do we set up DNS so if users can't connect through the Comcast IP, they are automatically redirected to the T1 IP?  And if they can't connect through the T1 IP, redirected to a third IP?
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OAC TechnologyProfessional NerdsAsked:
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Lee W, MVPConnect With a Mentor Technology and Business Process AdvisorCommented:
I've been using (and I normally would not recommend a linksys device) a Linksys RV042 - they are fairly inexpensive at about $150-200 and you can dig them up on ebay for $60-90 if you hit the right auction.  The device I'm using has performed pretty well and stable (though a VPN connection between it and a Netgear FVS114 has proven just a slight bit problematic as I'm having difficulty connecting over the VPN to a Win7 system with RDP (frequent protocol errors disconnecting me).  Other than that, it's worked great and I can't necessarily blame the device since going between brands CAN be problematic at best (looking to buy a second one myself).

Otherwise, you can get other devices - a more expensive option is a Fortigate by Fortinet - that works well as well - I have a client using one of those load balancing Cable internet (30/5) and a FiOS internet (25/25) line.

Though there are huge improvements in 2003 and later, it's generally considered UNWISE to run a server as your router.  And I don't know any software that would do this - and if it exists, it's likely going to cost MORE than the hardware devices I've mentioned.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
Having two gateways is not a reommended practice.  If you need a redundant connection, I suggest getting a router that's dual wan capable and that one router is your gateway.
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Neil RussellTechnical Development LeadCommented:
What you are trying to do is not achievable in the method you are trying.

No matter how many Nics you have, You should ONLY have 1 default gateway configured on ONE card. (The clue is in the word Default).

If you want redundancy you need to look at a router that supports multiple WAN connections.

Maybe something like the Cisco 1841 or 2801 router.
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rxdeathCommented:
yea not gonna happen. you're trying to do something that is much more complex than you think or can do by just adding a second nic.  multiple nics provide redundacy to a single gateway....like these guys said a special appliance is necessary, i recommend a barracuda link balancer since you don't sound like a cisco tech :).
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OAC TechnologyProfessional NerdsAuthor Commented:
Is there a software firewall that would accomplish the same thing so we don't need to purchase another hardware device?
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OAC TechnologyProfessional NerdsAuthor Commented:
These devices will give me the ability to go through different gateways which is great, but what about the redundancy portion?  This is a terminal server that needs to be up 24/7 and we need to have failover and redundancy when the internet connections go down.  How do other companies do this with a single DNS record that automatically rolls over to another IP address when internet fails?
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Lee W, MVPTechnology and Business Process AdvisorCommented:
These devices don't care about DNS.   If your DNS rolls over to the other IP, great... but these devices just accept incoming connections and, assuming you have them configured appropriately (especially the fortigate) they accept the incoming connection and feed it to your server (which if this is a critical system, I hope is clustered and on UPS and backup generator... And I hope you multiple internet connections are from different ISPs AND different technologies (why my client has FiOS and Cable).  The Fortigate can be configured in a redundant manner (the linksys, not to my knowledge).
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OAC TechnologyProfessional NerdsAuthor Commented:
I'm asking, how do I get DNS to roll over to the other IP addresses when one is down?
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Neil RussellTechnical Development LeadCommented:
Google round robbin dns. I'm on phone at the minute so can't to into detail.

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Lee W, MVPConnect With a Mentor Technology and Business Process AdvisorCommented:
For a TRUE high availability like that I believe you may need an ASN and BGP capable router and getting that setup can be challenging.  A Dual WAN router should allow you OUTBOUND communication without any issues if a line goes down.  INBOUND can be tricky at best.  Round Robin is NOT the answer since a round robin will alternate between the two (or more) listed IPs and if one goes down, you'll end up with timeouts HALF the time.  I know you may be looking to dumb this down as much as possible for your users, but then you should probably use a Hosted service to host the terminal server in the cloud or setup the dual wan router and provide two connections for your users and designate one as primary and the second as backup that the USER must try if the primary fails.

Note: When you have two gateways, you have a problem because the DEFAULT gateway is the one that should always be used, hence you can't have two that should always be used.  With dual gateways like that, data comes in one and potentially goes out the other and the receiver will not listen for a response from the other, that's why it won't work.

(What you're asking for is REALLY advanced and potentially very expensive networking/ISP configurations that small business DO NOT generally have unless they have HUGE revenues, in which case, they can afford it... )
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Neil RussellTechnical Development LeadCommented:
There is an excelent discussion here on what you are trying to achieve BUT as you will see, it's not easy and its complicated to set up and it can be expensive.

http://www.sadikhov.com/forum/index.php?showtopic=126251
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Neil RussellConnect With a Mentor Technical Development LeadCommented:
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OAC TechnologyProfessional NerdsAuthor Commented:
Is there a software firewall that would accomplish the same thing so we don't need to purchase another hardware device?

Also, would something like Windows 2008 Desktop Connection Broker be able to switch users to another server if the primary server was unreachable?
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